Why? It would make sense. Look at CVX, He was using robotic cameras. (albeit a little larger than a beetle) It's possible he was using them to spy on the events happening in each respective game they're in. Especially considering the fact that you can only find the RE4 beetle in one place in RE5, and that's by the docks in the cave shortly before the ruins. He probably put it there so he could see if Chris was able to get past Irving.